MTDNA PHYLOGEOGRAPHY AND POSTGLACIAL PATTERNS OF SUBDIVISION IN THE MEADOW GRASSHOPPER CHORTHIPPUS-PARALLELUS

A 300 bp portion of the mitochondrial cytochrome oxidase subunit I (CO I) gene was used to investigate the intraspecific genetic structure of the European meadow grasshopper Chorthippus parallelus. Levels of gen etic subdivision between geographical regions in Europe were assessed using the K-ST statistic and revealed patterns indicative of the postg lacial history of this organism. Northern European populations are sho wn to share a very recent common ancestor with, and hence originate fr om, a Balkan expansion. Genetic distances between these areas and both southern Italy and central Spain are shown to be approximately equal, even though only the Spanish form is recognized as a distinct subspec ies. Distance estimates indicate that the common ancestor of the two s ubspecies lived more than one glacial cycle ago, and the refugial popu lations have probably been diverging in isolation for five or six glac ial cycles (approximate to 550 000 years). Comparisons are made to the analysis of a similar data set using an anonymous nuclear DNA marker (Cooper et al., 1995). Although the structure revealed is generally ve ry similar, differences in the location of transition zones between di fferent genetic forms of C. parallelus may reflect the different histo rical assortment of these molecules.